Expansile protective cap for fluidic ordnance fuzes

ABSTRACT

An expansile protective cap designed to cover the intake and exhaust ports of an air driven power generator used in an electronic fuze. The cap is constructed of rubber or a rubberlike plastic that remains flexible over extreme temperature ranges and extended times of military interest. This expansile protective cap prevents the entrance of foreign matter into the ports and operating cavity of the generator and impeller before the projectile is fired from a gun. The protective cap is manually removable. However, this is not required. The cap has been designed and features have been incorporated therein such that the cap is automatically removed upon firing. The protective cap comprises a number of blind, oblong cavities located around its circumference. These cavities trap escaping propellant gas and force the skirt of the cap to expand outward. This expansion stretches the cap beyond a lip on the midbody of the fuze and blows it up somewhat like a balloon. Propellant gas escaping toward the end of the barrel of the gun upon entrapment by the cap automatically remove it. This entrapment action usually causes the cap to burst. The cap is scored to enhance the bursting action.

United States Patent 1191 Hines, Jr. June 4, 1974 EXPANSILE PROTECTIVE CAP FOR FLUIDIC ORDNANCE FUZES 57 ABSTRACT lnvemol'l Harold Hines, Fairfax, An expansile protective cap designed to cover the in- [73] Assigneez The United states of America as take and exhaust ports of an air driven power generarepresented by the Secretary of the tor used 1n an electron 1c fuze. The cap 1s constructed v Army, Washington DC of rubber or a rubber-hke plastlc that remams flexlble over extreme temperature ranges and extended times i Filed; J y 9 1972 of military interest. This expansile protective cap pre- [211 APPL No; 275,372 vents the entrance of foreign matter into the ports and operating cavity of the generator and impeller before the projectile is fired from a gun. The protective cap is US. Clmanually removab]e However this is not required [5 Cl- The cap has been designed and features have been in- Fleld of Search 91, corporated therein uch that the cap is automatically 102811812, removed upon firing. The protective cap comprises a number of blind, oblong cavities located around its Refel'fllces Cit! circumference. These cavities trap escaping propellant UNITED STATES PATENTS gas and force the skirt of the cap to expand outward. 1,850,196 3/1932 Bardsley l02/8l This expansion Stretches the cflp'beyohd a "P On the 2,987,999 6/1961 Robinson, Jr. et al 102/493 i y of the fuze and blows it p somewhat like 8 3,61 1,943 10/1971 Popper 102/812 balloon. Propellant gas escaping toward the end of the 3.714.900 2/l973 Feldmann l02/93 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-C. T. Jordan Attorney, Agent, or Firm-Edward J. Kelly; Herbert Berl; Saul Elbaum barrel of the gun upon entrapment by the cap automatically remove it. This entrapment action usually causes the cap to burst. The cap is scored to enhance the bursting action.

7 Claims, 3 Drawing Figures RIGHTS OF THE GOVERNMENT The invention described herein may be manufactured, used and licensed by or for the United States Government for governmental purposes without the payment to the inventor of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to an expansile protective cap for ordnance projectiles and, more particularly, to a plastic protective cap designed to keep foreign material from entering the operating cavity of a fuze fluidic generator which is automatically removed by the propellant gases of the projectile in order to facilitate the operation of the generator upon firing of the projectile. It is accordingly an object of this invention to provide an expansile protective cap for ordnance projectiles which prevents foreign matter from entering the fluidic operating cavity thereof.

It is also an object of this invention to provide an expansile protective cap for ordnance projectiles which is automatically removable by propellant gases escaping pastthe projectile as it is fired.

It is another object of this invention to provide an expansile protectivecap for ordnance projectiles which comprises a solitary monolithic structure.

Further objects and the entire scope of this invention will become fully apparent in the following detailed description and in the appended claims.

SUMMARY OF THE INVENTION The expansile cap for ordnance projectiles comprises essentially a structure for preventing the entrance of foreign matter into the operating cavity of a fluidic generator for powering an electronic fuze, blind oblong cavities located around the circumference of the cap for the entrapment of escaping propellant gas, and scoring on the outer surface of the cap such that the cap is easily exploded. The protective cap covers the intake and exhaust ports of an air driven power generatoruntil it is ready for utilization. The cover is constructed of rubber or rubberlike plastic that remains flexible over extreme temperature ranges and extended times of military interest. The blind oblong cavities located around the outer surface of the protective cap at the terminating edge trap propellant gases escaping around the periphery of the projectile upon firing in a gun tube. The gases escaping around the projectile through the space between the projectile and the gun wall possess high pressure and high velocity, and cause the flexible cap to expand over and beyond a retaining band located around the girth of the projectile. Once this occurs, the gases rapidly fill and expand the cap until it is exploded.

BRIEF DESCRIPTION OF THE DRAWINGS The specific nature of the invention as well as other objects, aspects, uses, and advantages thereof will clearly appear from the following descriptions and from the accompanying drawings, in which:

FIG. l is an exposed view of the expansile protective cap mounted on a projectile resting in a gun tube.

FIG. 2a is an exposed view of the protective cap illustrating the detailed structure.

2 FIG. 2b is a bottom view of the protective cap illustrating blind oblongcavitiestherein.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. I an embodiment of an expansile protective cap for preventing the entrance of foreign matter into the operating fluidic cavity of fluidally powered fuze is shown mounted on the forward end of said projectile. The protective cap 12 is formed to fit over the entrance ports and general nose area of the fuse 10. A groove 13 extends around the entire periphery of the fuze member 10 and provides a space into which mating band 24 extending around the entire internal periphery of the cap 12 may fit. Parallel'to the longitudinal axis of the projectile 11 are grooves 30. These grooves permit a portion of the propellant gas to escape beyond the projectile 11 into the slotted cavities 21. Expanding gases in the region 29 of the gun barrel [5 escape along the slots 30 and cause the protective cap 12 to expand outward at the point 28. This outward expansion releases the cap 12 from the nose 31 on the fuze 10. Scoring 40 is provided on the outer surface of the cap 22 such that the cap 22 is easily exploded. These scores 40 are dis persed about the surface of the cap 22 as shown in FIG. 2b.

In FIG. 2a is shown a more detailed illustration of the protective cap with a cutaway view of the internal design The external surface of the protective cap has a cross section resembling a Tudor arch. The internal surface area of the protective cap has a transverse cross sectional shape similar to that of a rounded arch. Blind I oblong cavities 21 are equally spaced around the terminating edge of the protective cap. These cavities are provided with enough depth to substantially react to a jet of propellant gass issuing around the projectile with a projectile nozzle velocity of at least 168 feet per second. Just before the terminating edge 25 of the protective cap at the point 23 the inside wall begins to thicken to form a band 24 that fits into a groove 13 located around the periphery of the fuze 10.

FIG. 2b illustrates the relative positions of the blind slots 21 formed adjacent to the terminating edge 25 of the protective cap. Note, the'slotted cavities 21 are equally spaced around principal longitudinal axis of the protective cap and possess rounded corners and hottoms.

The inventor wishes it to be understood that he does not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

What is claimed is:

I. An expansile protective cap for an ordnance projectile having an operating cavity comprising a flexible cup-shaped member fitted onto the nose end of said projectile and closed around the girth of said projectile; a plurality of equiformal cavities spaced around the periphery of said cap and oriented such that escaping propellant gas is trapped therein; and, means for destruction of said cap.

2. The expansile protective cap of claim 1 wherein said cavities are bilaterally and symmetrically spaced around the principal longitudinal axis of said cap and opening in the same direction as said cap.

3. The expansile protective cap of claim 2 wherein said cavities are located along the outer surface of the terminating edge of said cap.

plastic and rubber. I

7. The expansile protective cap of claim 6 wherein said member further comprises a band formed from said member and located along the inside terminating edge and coextensive with said edge of said member whereby said band fits into a groove formed on the periphery of said projectile. 

1. An expansile protective cap for an ordnance projectile having an operating cavity comprising a flexible cup-shaped member fitted onto the nose end of said projectile and closed around the girth of said projectile; a plurality of equiformal cavities spaced around the periphery of said cap and oriented such that escaping propellant gas is trapped therein; and, means for destruction of said cap.
 2. The expansile protective cap of claim 1 wherein said cavities are bilaterally and symmetrIcally spaced around the principal longitudinal axis of said cap and opening in the same direction as said cap.
 3. The expansile protective cap of claim 2 wherein said cavities are located along the outer surface of the terminating edge of said cap.
 4. The expansile protective cap of claim 3 wherein said means comprises scores dispersed about the surface of said cap.
 5. The expansile protective cap of claim 4 wherein said means is provided by the expandability of said flexible cup-shaped member whereby out rushing propellant gas causes said member to distend and explode.
 6. The expansile protective cap of claim 5 wherein said member is selected from the group consisting of plastic and rubber.
 7. The expansile protective cap of claim 6 wherein said member further comprises a band formed from said member and located along the inside terminating edge and coextensive with said edge of said member whereby said band fits into a groove formed on the periphery of said projectile. 